2. Discussion of the Background
In the paper industry, cores formed of a paper fiber material are utilized for winding a paper product thereon as the product is manufactured. Once the paper product is wound onto the core, the core and paper product are shipped to a customer or to another facility for use. For example, if the core is utilized for holding a supply of paperboard product to be utilized to manufacture cartons for frozen foods, after the paperboard product is wound upon the core, the core is shipped to the location at which the cartons are manufactured, and the core is utilized as the supply spool for the carton manufacturing equipment. Alternately, where the product is a towel or tissue product, the wound core can be transported to a location at which the product is unwound and cut to form consumer-sized portions or rolls of the product. Thus, the cores are utilized with a wide range of paper products for: (1) initial winding of the bulk paper product, (2) transportation of the paper product, and (3) unwinding of the paper product to form other products or different sized quantities of the product.
Typically, the cores are formed of a paper fiber material in which the paper is successively wound upon itself, with an adhesive material applied between each layer to bond the successive layers of paper as they are wound upon one another. The adhesive material can vary, and different adhesive materials can be utilized in a single core. For example, one type of adhesive can be utilized for inner layers of the core, with a different adhesive material utilized for subsequent layers, and possibly yet another adhesive material utilized for the outermost layers.
Once the paper fiber core has been formed and the adhesive has dried, a rigid core is obtained. The core is suitable for winding and subsequent handling of large quantities of paper products. The cores can have various diameters (typical inside diameters range from three to twelve inches) and lengths. The thickness xe2x80x9ctxe2x80x9d of the cores typically range from approximately three-eighths to one-half of an inch. FIGS. 1A and 1B depict an example of such a core. FIG. 1A depicts such a core 20 having a plug 22 inserted therein, while FIG. 1B depicts the plug 22 disassembled from the core 20. The plug is inserted into the end of the core. Only one plug 22 is shown in FIGS. 1A and 1B, however, it is to be understood that plugs are inserted into each end of the core. Also, for ease of illustration, a relatively short core is shown. Actually, the core is substantially longer than the plug. Core lengths typically range from 8 inches to 80 inches, while plug lengths typically range from one and one-eighth to one and one-half inches. During handling, the cores are typically gripped or clamped at their ends. The plugs are inserted into the ends of the cores to prevent the cores from collapsing during handling/transport. As shown in the drawings, the plugs typically include an aperture 24 to assist in removal of the plugs. For example, a rod can be inserted through the aperture 24 of one plug and used to push the plug at the opposite end from the core. The outside diameter of the plugs are tapered for better insertion and removal.
The plug has previously been formed with a molding process utilizing purchased wood shavings or chips, conventionally known as planters mill shavings. The planters mill shavings are fed through a hogger to break-down or decrease the size of the shavings, and then screened to provide wood particles of an appropriate size. Typically, the planters mill shavings must also be dried to decrease the moisture content in the shavings. After this processing, the wood particles are mixed with an adhesive, and then molded to form the plugs of a material similar to a particle board material.
Although such cores are sufficiently rigid for winding and unwinding of paper products, the cores can often become damaged or partially deformed after use, particularly as the fully wound cores are transported to the location at which the paper product is to be used or unwound from the core. In addition, the cores can be deformed in an unwinding operation, e.g., where a shaft is inserted into the core and pneumatically expanded to grip the inner surface of the core for an unwinding operation. Accordingly, the cores are typically not suitable for subsequent winding operations, and quite often the cores are used only once. Disposal of such cores can be problematic. Disposal in a landfill is wasteful of the material used in forming the cores. In addition, disposal of the cores is wasteful and costly in consuming landfill space. Moreover, if disposed in a landfill, it is sometimes necessary to break-down or cut-up the cores to reduce the landfill space, which can further increase the disposal cost.
Such cores can also pose difficulties if it is attempted to recycle the cores, for example, utilizing conventional paper recycling methods in which the paper material is re-pulped. The cores are problematic in this regard due to the significant amount of adhesive associated with the cores, which can lead to sticking problems when it is attempted to form the core material into another paper product. In order to practically utilize such cores in a repulping operation, it is believed that only a very small quantity of the core materials could be introduced with other paper product s and mixed with the other paper products, and even with this method, sticking problems could nevertheless result.
In view of the foregoing, a manner of disposing and/or recycling of paper fiber cores has been needed which avoids the wasteful disposal of such cores in landfills, while also avoiding the problems associated with repulping of the cores.
The invention provides a method and apparatus for converting paper fiber cores into molded products. Such products can include the plugs which are inserted into the ends of the core. However, the method and apparatus can also be utilized for molding other products as well. The present method and apparatus are environmentally advantageous in reducing the amount of wasted paper/wood products and landfill space associated with the disposal of such cores. In addition, the method reduces the cost and the amount of wood material required for forming molded products, including the plugs used with paper fiber cores, since the molded products are formed from the core materials rather than wood chips or shavings. Thus, the invention is advantageous economically, since the cost associated with disposal of the fiber cores is reduced and the cost of manufacturing of the molded products is also reduced.
With the present method and apparatus, the cores are initially mechanically broken down to form small particles. Where the molded product is a plug for paper fiber cores, the cores are preferably cut and then shredded to form small chip-size pieces or fiber bundles. In forming plugs, the resulting pieces are preferably confetti-size or the size of a match head (the particles are generally irregularly shaped, but preferably will have a size of approximately one-quarter of an inch or less, in terms of the largest dimension of the irregularly shaped particles). However, the size could vary depending upon the molded product to be manufactured and its strength requirements. The cut and shredded material is then fed through a blower to a separator device, which reduces the air in the material. Thereafter, a quantity of material needed to form a particular molded product is weighed to obtain the amount needed to form that product. Finally, the material is heated and compression-molded to form the final molded product. In accordance with the present method and apparatus, it has been recognized that the adhesives present in the paper fiber core are sufficient such that after the material has been mechanically broken down, it is not necessary to add additional adhesives to form the molded products. Also, it has been recognized that the moisture content typically present in such cores is such that it is not necessary to add moisture prior to molding. Further, the method is advantageous in that it avoids the need to repulp the paper utilized in such cores. Repulping is not only cost inefficient, but it also can be problematic due to the amount of adhesives associated with such cores as discussed earlier. As should be apparent, the invention is advantageous in many respects. One advantageous aspect of the present method and apparatus resides in avoiding the need for slurrying or repulping of the core material. In fact, the core material is preferably substantially dry throughout the process from the time the cores are mechanically broken down through the completion of the molding. As used herein, substantially dry means that the moisture content is below 20%. Preferably, the moisture content is below 15% and a moisture content in the range of 6-11% is particularly preferred. Since cores will typically have a moisture content in the 6-11% range when stored in normal ambient conditions, the method/apparatus is particularly advantageous in that neither the addition of moisture nor the drying of the material are required.